Quantitative evaluation of the changes of brain metabolits in rats with focal cerebral ischemia by using 1H magnetic resonance spectrum / 中国组织工程研究

ABSTRACT

BACKGROUND: Brain metabolic abnormality can be observed after cerebral ischemia.OBJECTIVE: To observe the changes of biochemical metabolism of rats with focal cerebral ischemia with 1H magnetic resonance spectroscopy (MRS) in order to reflect the metabolite abnormalities of rats during cerebral ischemic recovery phase.DESIGN: Randomized controlled study.SETTING: Departments of Neurology and department of Radiology of First Affiliated Hospital of Chongqing Medical University.MATERIALS The experiment was conducted at the Radiological Department of First Affiliated Hospital of Chongqing Medical University from April to July 2004. Totally 24 adult Wistar rats with clean grade were randomly divided into three groups, namely control group, sham operation group and cerebral ischemia group, with 8 rats in each group.METHODS: The focal cerebral ischemic model was established by occluding the right internal carotid artery in cerebral ischemia group and the filament were just inserted into the internal carotid artery not into the middle cerebral artery in sham operation group, nothing was done except for anesthetizing in the control group. 1H MRS was performed within the area of cerebral infarction and the homologous area of the contralateral hemisphere using 1.5T GE signa Highspeed MRI spectrometer in cerebral ischemic and shamed operation group at the following time point of 30 minutes, 1, 3, 6, 12, 24 hours, 3, 7, 15 days, 1 and 2 months after cerebral ischemia, and in the control group at the same time point.MAIN OUTCOME MEASURES: Changes of lactate, N-acetyl-aspartate (NAA), choline and creatine in infarct hemisphere and contralateral hemisphere.RESULTS: Totally 24 rats were selected in the study, but two died of anesthesia in sham operation group and four of serious brain edema in cerebral ischemia group, only 18 rats entered the final analysis with 8 in normal control group, 6 in sham operation group and 4 in cerebral isThe marked increase in NAA, choline and creatine was recognizable in bilateral spectra 30 minutes after cerebral ischemia and decreased to the period of 3-6 hours, but there was no significant difference in NAA, choline at 6 hours and reached the lowest level at 24 hours (45.21±0.37), choline (93.80±0.56) and creatine (69.33±0.44) at 3 days, and then NAA, choline and creatine gradually increased over time. The increase in NAA was especially obvious which increased by 2.5 times at 2 months than that at 24The earliest detection of lactate was at 10 minutes within the infarct. The lactate concentration elevated at 1 day and peaked at 12 hours, and a partial recovery of the reduction of lactate was seen at 3 days, and the lactate increase within the infarct region was significant compared with that of the homologous area (66.83±0.43,44.35±0.35, t=2.379, P ＜ 0.05). However, the elevation in lactate was no longer observed during the period of up to 2month follow-up.ischemia and reflect the metabolites changes in brain of rats after cerebral cerebral ischemic recovery phase objectively.